Optical lens.



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OPTICAL LENS.

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1,143,316. Patented Jim e 15, 1915.

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A. G. POULLAIN & D. H. J. CORNET.

OPTICAL LENS. APPLICATION FILED JULY 18. 191i.

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OPTICAL LENS.

APPLICATION FILED JULY 18.

UNITED STATES PATENT OFFICE.

AUGUSTIN GEORGES POULILAIN AND DARIUS HENRI J'ULIEN CORNET, OF PARIS,FRANCE.

OPTICAL LENS.

Specification of Letters Patent.

Patented June 15, 1915.

To all whom it may concern:

Be it known that we, Ancusrm Gnoncas POULLAIN, of 44 Rue de Eurbigo,landlord, and DARIUS HENRI JULIEN CORNET, of 66 Rue de Rennes, Optician,both in the city of Paris, Republic of France, have inventedImprovements in and Relating to Optical Lenses, of which the followingis a full, clear, and exact description.

The lenses employed in optics to enable long-sighted, very long-sightedor shortsighted people and also those who have been operated on forcataract to see far and near and known by the names of Franklin lenses,double focus lenses, whether in a single piece or assembled, present theinconvenience that they only give distinct vision for given distancescorresponding to the focal lengths of the upper part and the lower partof the lens but not giving distinct mages to the eye for intermediatedistances. Furthermore there is a line of demarcation between the twoportions of the lens which is liable to produce diplopia and the eye issubjected to a certain amount of strain when it looks over this line.

The present invention has for its object a form of lens remedying thesedefects and allowing by its special constitution to see not only nearand far but also at intermediate distances.

This lens is essentially characterized by this fact that it presents onone of its faces, or on both, surfaces with radii of variable curvatureuniformly progressive; these surfaces can be combined with surfaces ofthe same kind or with other surfaces of constant radii of curvature,they can also be joined with each other or with surfaces of constantradii of curvature.

The accompanying drawings show, by way of example, the present form oflens and means for'the practical realization of its surfaces withprogressive radii of curvature.

Figure 1 shows a spiral with radii of curvature varying in a continuousmanner, this spiral showing at a greater scale the main section of oneof the faces of the presout form of lens; Fig. 2 shows the main sec tionof a lens made according to the present invention; Fig. 3 is a sectionmade according to line bb of Fig. 2. Figs. 4 to 18 illustratemodifications in the manufacture of the present form of lens.

This form of lens is based, as mentioned above, upon the employment ofsurfaces with radii of variable curvature uniformly progressive in acontinuous manner either as regards one or both the faces of the lens.Considering such a lens arranged before the eye and sectioned by a planeperpendicular to the line of the eyes (that is to say the plane of thepicture in Fig. 1) and passing through the center of the pupil, thissection will be designated the principal section.

One at least of the faces of the lens will give as intersection withthis plane instead of a circular curve or a succession of circularcurves limited in number as in the single, double or triple focus lensesreferred to above, a curve with variable radii of curvature uniformlyprogressive in a continuous manner such as a spiral a b 0 d/-- forexample the radii of curvature a a b b c c d d of which vary in acontinuous manner.

If we consider a second section of th lens on a plane passing through asection 0 0 normal to this curve at any of its points a andperpendicular to the plane of the principal section the same face of thelens will give as intersection with this plane, either a circular curveof radius equal or unequal to the radius of curvature of the principalsection at this point or even a straight line (this is the case ofcylinders, the generating lines of which are perpendicular to theprincipal section}. The second face of the lens will be a surface of thesame kind as the first or a sphere, a plane, a cylinder, a torus.

Example: Given the problem of correcting a slight requiring N. dioptersfor seeing at a distance and N, diopters for near vision withoutcorrection of astigmatism.

The principal section of the first face A (Fig. 2) of the lens will be acurve with variable radii of curvature uniformly progressive in acontinuous manner and determined in accordance with the index ofrefraction of the material employed insuch a manner that they give arefringenoe of ndiopters in the upper art of the lens and n, in thelower part. or every section perpendicular to the principal section atany one of its points and passing through the normal 0 c to this sectionat this point (Fig. 3), any desired conditions can be im for example,that this second section shall be a portion of a circumference withradius equal to the radius of curvature b b of the principal section atthis point e.

The second face A of the lens may be either a surface of the same kind(Figs. 2 and 4) of n, diopters in the upper part of the principalsection and n, in the lower part 11,, n',, m, n',, N. N, being selectedin uch a manner that the following equations are Obtained:

- r a sphere of n. diopters (Figs. 5 and 6) wlh the conditions:

or a sphere of the curvature of -'n'. diopters (Figs. 9, 10, 11, 12)with the conditions:

and in this manner lenses analogous to conergent or divergent minisciare obtained.

A plane (Figs. 13, 14) mi ht also be taken as the second surface with econditions:

o= o s= r which would give lenses analogous to ordinary lano-convex andpiano-concave lenses.

In cases where it is at the same time desired to correct asti atism thesecond surface may be a cylin or or a torus. The cylinders of the torimay have as their principal section a circumference or a curve withvariable radii of curvature which will give lenses analogous tohero-cylindrical and toric lenses. Itis a possible to combine twocylinders or a cylinder and a torus or two tori, one or both of thempresenting princial sections of variable radii of curvature y incliningthe axes one to the other in order to obtain lenses analogous to thosetermed Ohamblant lenses.

The curvsrs of uniformly pro 've curvature employed for the principalsection may be either spirals (archimodian, logarithmic, multiplecenter, circular evolvent spirals, and so forth), arcs of ellipse,parabola, hyperbola curves of the second degree or of higher degrees,algebraic or transcendent, symmetric or nonsymmetric curves.

The present form of lens can be combined in such a manner that itslowest part enables the person who wears the same to see the ground atits feet without bein compelled to lower the head in a very sensi leway. In this case, the principal section of this type of lens may beconstituted by a curve such that in the downward direction the radius ofcurvature diminishes to a minimum and then increases progressively, orvice versa. This result ma be obtained either by choosing the law 0variation of this radius of curvature in such a manner that the increaseof this radius is first of all negative and then becomes positive or bytaking a curve which is symmetrical relatively to an axes or by taking anon-symmetrical curve and joining it with another curve and proceedingin such a manner that at their point of connection the two curves havethe same tangent and the same radius of curvature.

In accordance with special forms of vision the lens will present on oneof its faces a surface having as its principal section the system ofcurve defined above and on the other face either a surface of the samekind or a spherical cylindrical, toric, conical or other surface. Theprincipal section of the lens may also be constituted by two curves eachcomposed of a portion in which the radius of curvature increases ordecreases and of a portion in which the radius of curvature remainsconstant, these two curves being arranged opposite each other in such amanner that the portion with an increasing or decreasing radius ofcurvature of each of these curves corre onds to the portion withconstant radius 0 curvature of the other curve.

Fig. 15 illustrates a method of obtaining a lens of this kind, intendedfor a person having under one an operation for cataract requiring 16iopters for near vision and 12 'diopters for distant vision. In theprincipal section represented in this figure the front face comprises:(a) An up er half the radius of curvature of which ecreasesprogressively from the upper extremity to the median part, its difierentpoints corresponding to 4, 5, 6, 7 and 8 diopters. (b)A lower half theradius of curvature of which is constant and correspond to the value of8 diopters. The rear face of the lens is constituted by a similar butinverted curve in such a manner that the half of each face withdecreasing radius of curvature is o posite the portion with constantradius 0 curvature of the other face.

Considering the different levels of :he

princifial section in the downward direction the fo owing results areobtained: At the upper part:

. 4+s =12 Then:

5+sr=1a e+s=14 7+s =1a the median part:

, 8+8=16 Then below:

' 8"+7=='15 '8+6=14 sea-5 :1? At the lower part:

part A A and lower parts A A are sp erical and their radii arerespectively equal to the radii of curvature of the extreme points A Aof the central part with which these spheres are thus connected withoutany lineof demarcation. r.

Fig. 18 shows a lens more particularly intended for persons who havebeen operated on for cataract. This lens comprises :At its upper'part, asurface A A of constant radius allowing to see far,above the latter asurface A A with variable radii of ourvature progressively decreasing,allowing to see at intermediate distances, the part A allowing to seenear,this surface is prolonged with a surface A A with radii ofcurvature progressively increasing and enabling to see at intermediatedistance toward the ground ;--this surface can be prolonged with anothersurface A" A of constant radius allowing the person who wears this lensto see at its feet with a sufiicient field of view.

Considering the section defined in the lens by a plane perpendicular tothe principal section defined above pam'ng through a point of the curveof the latter and by the normal to this curve at this point this sectionwill be a portion of a circumference of a radius equal or unequal to theradius of curvature of the principal section at this point; by givingthese two radii suitably selected unequal values the correction of astiatism can be introduced.

n cases where the two faces of the lens are constituted by fragments ofcylinders, the axes of which intersect while the puncipal sections arecurves of the kind indicated above either symmetrical or unsymmetricalastigmatism can be corrected in inclining the axes of the twocylindrical surfaces one to the other not-exactly at right angle whichmust be determined in accordance with the defect to be corrected.

In order to obtain the surfaces indicated above, the methodsordinarily-employed by Opticians .for cutting spherical, cylindrical ortoric lenses would not be suitable and that it would be necessary tohave recourse to special machines.

Claims:

1. A spectacle glass with multiple foci,

presenting, on one of its faces, a surface determined: on the one handby a directrix curve s1tuated in the principal section of this glass, 1nthe direction of its height and such that the radii of curvature of itsdifierent points vary progressively in a continuous manner,-an eratrixcurves cutting this curve andconstitutcd by circumferential arcssituated in planes perpendicular to the principal section of the glassand normal to the said curve.

2. A spectacle glass with multiple foci, presenting on its two faces, asurface determined: on the one hand by a directrix curve situated in theprincipal section of this glass, in the direction of its height and suchthat the radii of curvature of its different points on the other hand bygenvary progressively in a continuous man- 7 ner,and on the other handby generatrix curves cutting this curve and constituted bycircumferential arcs situated in planes perpendicular to the principalsection of the glass and normal to the said curve.

3. A spectacle glass with multiple foci, presenting on one of its facesa surface determined,--on the one hand by a directrix curve situated inthe principal section of this glass in the direction of its height, andcomposed of parts such that the radii of curvature at the differentpoints of the said parts vary progressively in a continuous manner andof other parts of constant radius of curvature, and on the other hand bygeneratrix curves cutting the directrix curve and constituted bycircumferential arcs, situated in planes perpendicular to the principalsection of the glass and normal to the said curve.

4. A spectacle glass with multiple foci, presenting, on one of itsfaces, a surface determined: on the one hand by a directrix curvesituated in the principal section of this glass, in the direction of itsheight and such that the radii of curvature of its difier- I a b i l ofcurvature of the directrix curve at its points of intersection with saidgeneratrix curves.

5. A spectacle glass with multiple foci, presenting on one of its faces,a surface determined: on the one hand by a directrix curve situated inthe rincipal section of this glass, in the directlon of its height andsuch that the radii of curvature of its different points varyprogressively in a continuous manner,and on the other hand by generatrixcurves cutting this curve and constituted by circumferential arcssituated in planes perpendicular to the principal section of the glassand normal to the said curve, these generatrix curves having equal radiiof curvature.

, 6. A spectacle glass with multiple foci, presenting, on one of itsfaces, a surface determined: on the one hand by a directrix curvesituated in the principal section of this glass, in the direction of itsheight and such that the radii of curvature of its different points varyprogressively in a continuous manner,-and on the other hand bygeneratrix curves cutting this curve and constituted by circumferentialarcs situated in planes rpendicular to the principal section of t e glasand normal to the said curve, these generatrix curves having radii ofcurvature varying among themselves in a constant manner.

The f0 oing specification of our improvements m and relatingato o ticallenses signed by us this seventh y ofJuly, 1911.

- AUGUST!!! GEORGES POULLAIK.

DARIUB HENRI JULIE] CORNET. Witnesses:

H. 0. Cohen, R. Turner.

